Count work days between two dates

Question

How can I calculate the number of work days between two dates in SQL Server?

Monday to Friday and it must be T-SQL.

Answer 1

Another approach to calculating working days is to use a WHILE loop which basically iterates through a date range and increment it by 1 whenever days are found to be within Monday – Friday. The complete script for calculating working days using the WHILE loop is shown below:

CREATE FUNCTION [dbo].[fn_GetTotalWorkingDaysUsingLoop]
(@DateFrom DATE,
@DateTo   DATE
)
RETURNS INT
AS
     BEGIN
         DECLARE @TotWorkingDays INT= 0;
         WHILE @DateFrom <= @DateTo
             BEGIN
                 IF DATENAME(WEEKDAY, @DateFrom) IN('Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday')
                     BEGIN
                         SET @TotWorkingDays = @TotWorkingDays + 1;
                 END;
                 SET @DateFrom = DATEADD(DAY, 1, @DateFrom);
             END;
         RETURN @TotWorkingDays;
     END;
GO

Although the WHILE loop option is cleaner and uses less lines of code, it has the potential of being a performance bottleneck in your environment particularly when your date range spans across several years.

You can see more methods on how to calculate work days and hours in this article: https://www.sqlshack.com/how-to-calculate-work-days-and-hours-in-sql-server/